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NOUS41 KWBC 231447 AAA

Technical Implementation Notice 16-26 Amended
National Weather Service Headquarters Washington DC
1047 AM EDT Tue Aug 23 2016

To:  Subscribers:
  -NOAA Weather Wire Service
  -Emergency Managers Weather Information Network
  Other NWS Partners, Users and Employees

From:  Tim McClung
  Portfolio Manager
  Office of Science and Technology Integration

Subject:  Amended: Upgrade to the Rapid Refresh (RAP) and the
  High-Resolution Rapid Refresh (HRRR) Analysis and
  Forecast System Effective August 23, 2016

Amended to change the date from "future" to August 23 for select
products under the NOAAPORT changes section below.

Effective on or about Tuesday, August 23, 2016, beginning with
the 1200 Coordinated Universal Time (UTC) run, the National
Centers for Environmental Prediction (NCEP) will implement
Version 3 of the Rapid Refresh (RAP) and Version 2 of the High-
Resolution Rapid Refresh (HRRR) systems.

Major Changes:

A major change to the RAP will be an expanded computational
domain which will now include Hawaii. This expansion will
facilitate future NCEP plans for ensemble systems and, in time,
improve the initialization of Short Range Ensemble Forecast
(SREF) members that use the RAP for initial conditions.

Analysis Changes:

Both the RAP and HRRR will use an updated version of the
Gridpoint Statistical Interpolation (GSI) analysis code.
Refinements are made to the GSI to improve the assimilation of
surface observations, soil moisture adjustment, and three-
dimensional cloud and precipitation hydrometeors. In addition,
the HRRR will start using the ensemble/hybrid data assimilation;
it is already used in the RAP, but the weighting of the ensemble-
based component in the RAP will increase from 0.50 to 0.75. In
addition, while the RAP already cycles land-surface states, this
cycling is being introduced into the HRRR. In HRRR Version 1, all
runs are independent.

Other analysis changes include:

-Assimilating radial wind and mesonet data
-Applying PBL-based pseudo-innovations for 2-meter temperatures
(already used for 2-meter dew points)
-Changing the cloud-hydrometeor assimilation to avoid METAR-based
cloud building when satellite data shows clear skies at all times
of day (currently used just in daytime)
-Introducing direct use of 2-meter temperature and dew point
model diagnostics in the GSI.

Specific to the HRRR, the application of radar reflectivity data
in the GSI to direct specification of 3-dimensional hydrometeors
is increased to apply to a broader range of weather conditions,
including warm-season events with reflectivity up to 28 dBZ.

Changes to Model:

- The RAP and HRRR will both begin using WRF version 3.6.1; both
will continue to use the ARW core.
- The MYNN planetary boundary layer scheme is being updated to
include the effects of subgrid-scale clouds. The mixing length
formulation in the boundary layer scheme and thermal roughness in
the surface layer are being changed.
- The 9-level RUC land-surface model is being updated to add a
mosaic approach for fractional snow cover, improve the fluxes
from snow cover, and modify the wilting point for cropland use.
- Major updates are being made to the Thompson microphysics
scheme, including making it aerosol-aware with use of an ice-
friendly and water-friendly aerosol field.
- Shortwave and longwave radiation have been changed to use the
RRTMG (RRTM global) scheme that includes the effects of aerosols
and boundary layer subgrid-scale clouds.
- The WRF-ARW diagnostics for 2-meter temperature and dew point
are being improved.
- The convective scheme in the RAP is changed from the Grell 3-D
scheme to the scale-aware Grell-Freitas scheme. The HRRR, at 3 km
horizontal resolution, explicitly resolves convection and does
not use a convective scheme.

Many of these changes to the data assimilation, land-surface
model, boundary layer scheme, microphysics, radiation, and (in
the RAP only) convective scheme are designed to mitigate the low-
level warm, dry bias in the RAP and HRRR, most notable during
afternoons in the warm season. Significant reduction of these
biases has been evident in extensive testing.

Output Changes:

- The HRRR directory structure will be migrated out of
"nonoperational" on the NCEP ftp and http servers. Data will also
be available on both the primary and secondary servers.


- The forecast lengths of both the RAP and the HRRR will be
extended on the NCEP servers:

The RAP hourly output will be extended from 18 to 21 hours for
all cycles. The HRRR hourly output will be extended from 15 to 18
hours for all cycles.

Output files will be written directly to GRIB2 instead of first
being written out to GRIB1 and converted to GRIB2. Users may see
some differences with the encoding and are encouraged to upgrade
their software to handle this. Please see the links below for
upgraded code:

- The following GRIB1 RAP output is being discontinued on NCEP
and NWS servers. The 40km Regional RAP will be discontinued here
only. There will be no impacts to NOAAPORT.

The GRIB2 equivalent is online at:

Where CC is cycle, FF is forecast hour (00-21), YYYYMMDD is year,
month and day

- The following file names will change to remove "tm00":

rap.tCCz.wrfprsHH.tm00.grib2 -> rap.tCCz.wrfprsfHH.grib2

rap.tCCz.wrfnatHH.tm00.grib2 -> rap.tCCz.wrfnatfHH.grib2

Where CC is the cycle (00-23), and HH is the forecast hour (00-

- In conjunction with the expansion of the RAP domain, output on
a new forecast grid will be added to the NCEP ftp/http servers,
opendap and grib filter.  RAP output on grid 243, which covers
Hawaii and the eastern Pacific Ocean, will be available with




Where CC is the cycle (00-23) and FF is the forecast hour (00-21)

- The 3-hr pressure tendency field, available in several RAP
output grids, will no longer be available. Users will need to
compute this parameter on their own.

- The value that represents the resolution and component flags of
the grid definition template is changed in all RAP output from 8
to 56. This indicates the resolved u and v components of vector
quantities are relative to the defined grid in the direction of
increasing x and y (or i and j) coordinates, respectively, and
the i and j direction increments (representing dx and dy of the
model) are stored within the grid definition templates for all
RAP output grids.

- The labeling of the following RAP parameters are being
modified, mainly due to different conventions in the way direct
grib2 output is post-processed. These changes apply to any and
all RAP output grids on which the parameter is found:

    Composite reflectivity (Discipline 0, Category 16,
    Number 196):  The fixed surface type is changed from
    200 (Entire Atmosphere (considered as a single layer))
    to 10 (Entire Atmosphere).

    U and V components of storm motion (Discipline 0,
    Category 2, Numbers 194 and 195):The current
    labeling of the first specified height level above
    ground as 6000 and the second level as 0 is changed so
    that 0 is the first level and 6000 is the second.

    U and V components of vertical wind shear (Discipline
    0, Category 2, Numbers 15 and 16):  The current
    labeling of the first specified height level above
    ground as 6000 and the second level as 0 is changed so
    that 0 is the first level and 6000 is the second.

    Total Cloud Cover (Discipline 0, Category 6, Number
    1):  The fixed surface type is changed from 200
    (Entire Atmosphere (considered as a single layer))
    to 10 (Entire Atmosphere).

    Soil Moisture availability (Discipline 0, Category 0,
    Number 194):  The fixed surface type is changed from 1
    (surface) to 106 (depth below land surface), with the
    depth specified at 0 meters.

    Relative humidity computed with respect to
    precipitable water (Discipline 0, Category 1, Number
    242):  The fixed surface type is changed from 200
    (Entire Atmosphere (considered as a single layer)) to
    10 (Entire Atmosphere).

    For all soil moisture (Discipline 2, Category 0,
    Number 192) and soil temperatures (Discipline 2,
    Category 0, Number 2), the fixed surface type is still
    106 (depth below land surface), but the depth is now
    reported as a range between 2 levels (with the chosen
    level listed as both levels) instead as a single
    level.  As an example, soil moisture at 40 cm is
    currently listed as soil moisture at a depth of 0.40
    meters; it will now be listed as soil moisture between
    a depth of 0.4 meters and 0.4 meters.

- Changes to Labeling of Parameters in the HRRR

    For the lightning flash rate (Discipline 0, Category
    17, Number 192), the fixed surface type is changed
    from 1  (Surface) to 10 (Entire Atmosphere).

    The sea level pressure field (Discipline 0, Category
    3, Number 1) is replaced by an alternate sea level
    pressure field (Discipline 0, Category 3, Number 198)
    to be consistent with the RAP.

    The best lifted index field (Discipline 0, Category 7,
    Number 11) is changed to Discipline 0, Category 7,
    Number 193, making it consistent with the RAP.

    The number of concentration of ice particles is
    changed from Discipline 0, Category 1, Number 207 to
    Discipline 0, Category 6, Number 29

    The number of concentration of rain is changed from
    Discipline 0, Category 255, Number 255 to Discipline
    0, Category 1, Number 100

- RAP Precipitation Fields

The RAP currently generates convective and non-convective
precipitation totals. Total precipitation will be added to the
output so users no longer need to sum the convective and non-
convective amounts. To become consistent with other NCEP models
that generate only total and convective precipitation, the run
total and 1-hour accumulation non-convective precipitation fields
will be eliminated in the 2017 RAP Version 4 upgrade. Users
should start preparing for this change but all three
precipitation parameters will be provided in RAP Version 3 to
assist with the transition.

For the precipitation fields, RAP files currently contain run
total and 1-hr accumulations for all forecast hours. In addition,
forecast hours 5, 8, 11, 14 and 17 contain an additional 2-hour
accumulation, while forecast hours 6, 9, 12, 15 and 18 contain an
additional 3-hour accumulation.   The 2-hour accumulations will
be discontinued in all output files on NCEP and NWS servers but
will be retained in files sent to AWIPS. The 3-hour accumulations
at hours 6, 9, 12, 15, 18 (and 21) will be retained.

Similar changes are made to the snow water equivalent field. The
RAP output grids right now contain various combinations of
instantaneous, run total, and 1, 2 or 3-hour accumulation of snow
water equivalent.  The output will be unified so that all grids
at all output times have instantaneous, run total, and 1-hr
accumulation of snow water equivalent.The files for all
forecast hours divisible by 3 will contain 3-hour accumulations
of snow water equivalent.  These snow water equivalent
accumulations are being changed to contain contributions only
from snow hydrometeors.

Two new winter precipitation fields are being added - accumulated
snow depth that includes variable density hydrometeor
accumulation and snowmelt affects (Discipline 0, Category 1,
Number 29) and accumulated graupel  (Discipline 0, Category 1,
Number 227), both available in 1-hour and run total amounts. Note
that the parameter listing is for frozen rain because no
parameter currently exists for graupel.

- Changes to RAP Cloud Base Height / Ceiling

The RAP output currently contains a parameter called cloud base
height (fixed surface type 2) which actually represents the cloud
ceiling. In this upgrade, cloud base height will actually
represent the true cloud base height, and the old computation is
now properly labeled as cloud ceiling (fixed surface type 215).
This makes the RAP consistent with the current operational HRRR.

- Added and Removed RAP and HRRR Parameters:

A full list of parameters added to and removed from all RAP and
HRRR output grids can be found at:

Changes to NOAAPORT:

With this upgrade, the volume of data transmitted over NOAAPORT
will increase due to GRIB packing changes:

RAP 13km increase 80MB/cycle
RAP 40km increase 6MB/cycle

On August 23, NCEP will add the following products to NOAAPORT.
Please see the following documents for the details of these:

RAP Puerto Rico:

RAP 13km extended hourly forecast hours:
Please note that there are WMO header changes within this link
detailing changes from level 98 to level 86 for multiple

HRRR extended hourly forecast hours:

In the future, when AWIPS is ready, the following products will
be delivered to NOAAPORT. Please see the document for details:

HRRR sub-hourly output:

Product Delivery Times:

HRRR analysis products are available approximately 6 minutes
later in Version 2, but the delay is diminished as the forecast
progresses such that the products arrive 2 minutes earlier by
forecast hour 15. RAP analysis products are available 3 minutes
later in Version 3, but the delay is diminished as the forecast
progresses such that the products arrive at the same time by
forecast hour 18.

Parallel Data Location:

A consistent parallel feed of data is available on the NCEP
server via the following URLs:

For more general information about the RAP and HRRR, please see:

NCEP urges all users to ensure their decoders can handle changes
in content order, changes in the scaling factor component within
the product definition section (PDS) of the GRIB files, and
volume changes. These elements may change with future NCEP model
implementations. NCEP will make every attempt to alert users to
these changes before implementation.

For questions regarding this implementation, please contact:

     Geoff Manikin
     NCEP/EMC/Mesoscale Modeling Branch
     College Park, MD

     Curtis Alexander
     ESRL / Global Systems Division
     Boulder, Colorado

For questions regarding the data flow aspects of these datasets,
please contact:

    Carissa Klemmer
    NCEP/NCO Dataflow Team Lead
    College Park, Maryland 20746

NWS National Technical Implementation Notices are online at: is the U.S. government's official web portal to all federal, state and local government web resources and services.